The Engineering Case For Fusing Your LED Strips

January 29, 2018 by Lewin Day 46 Comments

Modern LED strips are magical things. The WS2812 has allowed the quick and easy creation of addressable RGB installations, revolutionizing the science of cool glowy things. However, this accessibility means that it’s easy to get in over your head and make some simple mistakes that could end catastrophically. [Thomas] is here to help, outlining a common mistake made when building with LED strips that is really rather dangerous.

The problem is the combination of hardware typically used to run these LED strings. They’re quite bright and draw significant amounts of power, each pixel drawing up to 60 mA at full-white. In a string of just 10 pixels, the strip is already drawing 600 mA. For this reason, it’s common for people to choose quite hefty power supplies that can readily deliver several amps to run these installations.

It’s here that the problem starts. Typically, wires used to hook up the LED strips are quite thin and the flex strips themselves have a significant resistance, too. This means it’s possible to short circuit an LED strip without actually tripping the overcurrent protection on something like an ATX power supply, which may be fused at well over 10 amps. With the resistance of the wires and strip acting as a current limiter, the strip can overheat to the point of catching fire while the power supply happily continues to pump in the juice. In a home workshop under careful supervision, this may be a manageable risk. In an unattended installation, things could be far worse.

Thankfully, the solution is simple. By installing an appropriately rated fuse for the number of LEDs in the circuit, the installation becomes safer, as the fuse will burn out under a short circuit condition even if the power supply is happy to supply the current. With the example of 10 LEDs drawing 600 mA, a 1 amp fuse would do just fine to protect the circuit in the event of an accidental short.

It’s a great explanation of a common yet dangerous problem, and [Thomas] backs it up by using a thermal camera to illustrate just how hot things can get in mere seconds. Armed with this knowledge, you can now safely play with LEDs instead of fire. But now that you’re feeling confident, why not check out these eyeball-searing 3 watt addressable LEDs?

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Disco Bulb Keeps The Party Spinning

January 27, 2018 by Kristina Panos 12 Comments

Even if you don’t like disco, you might like the slick moves that went into this project. [W&M] built a miniature motorized mirror ball inside of a standard incandescent light bulb, and the results are something to dance about.

Short of blowing a glass bulb, building a motor, and growing the wood, this is about as scratch-built as it gets. Much of the woodworking is done on a metal lathe, and this includes the base of the mirror ball itself. As with all good thing-in-a-bottle builds, the ball is too big to go in the bulb, so [W&M] quartered it, drilled a few holes, and ran a string through the pieces so they can be carefully glued and drawn back together into a sphere. He even cut up mirror tiles and painstakingly applied them with tweezers.

This disco bulb is meant to be hung from the ceiling and wired into mains like a regular mirror ball. [M&W] stuffed the guts from a small USB wall charger into the handmade beech base to provide clean power for both the geared motor that spins the ball and the tiny LED that illuminates it. Slip into your best leisure suit (or sweat suit, we won’t judge) and hustle past the break to watch the build video.

We don’t see a lot of disco balls around here, but we did see a disco icosahedron once.

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Counting Is For Sheep: Use A Light To Fall Asleep

January 26, 2018 by Kristina Panos 12 Comments

How do you get to sleep at night? For some of us, it can be the most difficult thing we do all day. Worrying about falling asleep and letting other intrusive thoughts in night after night only compounds the problem, as less sleep leads to depression which (for us) leads to even less sleep. We lay there, trapped inside a vortex of churning thoughts, imprisoned in a mind that feels like it’s malfunctioning and half-wishing for a future where instructor-led meditation videos can be beamed to the insides of our eyelids. In the meantime, there is FADing, the Fall Asleep Device.

FADing takes its cues from a relaxation technique that uses light to focus your attention and control your breathing. The light’s intensity waxes and wanes on a schedule designed to get you down from the average eleven breaths per minute to a zen-like six breaths per minute. You surrender to the light, breathing in as it intensifies and breathing out as it fades. There are commercial products that bring this technique to the bedroom, but they aren’t cheap and don’t offer much control. Fail to fall asleep in the prescribed window and you’re back to square one with one more thing to think about: buyer’s remorse.

[Youz] was inspired by these devices but dissatisfied with the price tag and lack of options, so he created his own version with a flexible window of operation that appeals to both back- and side-sleepers. It uses an Arduino Nano and two momentaries to control two LEDs, a relay to hold the power after startup, a 9V, and a diode to protect the Nano. One LED projects on the ceiling, and the other radiates through a slice of acrylic which has been shaded blue. One button is for power, and the other lets you add time by two-minute increments. You can see the build video after the break and then tell us how you’d do it with a 555, a coin cell, and a chunk of uranium glass in the comments.

Once you can focus on your breathing without a light, reuse that Nano to measure the quality of all that sleep you’re getting.

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Giving Stranger Things For Christmas

January 24, 2018 by James Hobson 5 Comments

[rudolph] was at a loss on what to get his niece for Christmas. It turns out she’s a huge fan of Stranger Things, so the answer was obvious: make her an alphabet wall she can control!

Downsizing the scale to fit inside a document frame, [rudolph] calls their gift rudLights, and a key parameter of this build was to make it able to display any phrases sent from their niece’s Amazon Fire tablet instead of constantly displaying hard-coded phrases. To do so, it has a HC-05 Bluetooth module to forward the commands to the NeoPixel LEDs running on a 5V DC power supply.

[rudolph] enlisted the help of their son to draw up the alphabet display — printed straight onto thematically decorative wallpaper — and cut out holes in the light bulbs for the LEDs. Next up was cut some fibre board as a firm backing to mount the electronics inside the frame and drill holes for the NeoPixels. It was a small odyssey to cut and solder all the wires to the LEDs, but once done, [rudolph] divided their rudLight alphabet into three rows and added capacitors to receive power directly.

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DIY Dungeon Crawler Game Plays On Single LED Strip

January 24, 2018 by Donald Papp 23 Comments

A delightful version of a clever one-dimensional game has been made by [Critters] which he calls TWANG! because the joystick is made from a spring doorstop with an accelerometer in the tip. The game itself is played out on an RGB LED strip. As a result, the game world, the player, goal, and enemies are all represented on a single line of LEDs.

How can a dungeon crawler game be represented in 1D, and how is this unusual game played? The goal is for the player (a green dot) to reach the goal (a blue dot) to advance to the next level. Making this more difficult are enemies (red dots) which move in different ways. The joystick is moved left or right to advance the player’s blue dot left or right, and the player can attack with a “twang” motion of the joystick, which eliminates nearby enemies. By playing with brightness and color, a surprising amount of gameplay can be jammed into a one-dimensional display!

Code for TWANG! is on github and models for 3D printing the physical pieces are on Thingiverse. The video (embedded below) focuses mainly on the development process, but does have the gameplay elements explained as well and demonstrates some slick animations and sharp feedback.

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Interactive LED Table

January 21, 2018 by Al Williams 6 Comments

Some hackers make functional things that you can’t allow to be seen in polite company. Others make beautiful things that could come from a high-end store. [Marija] falls into the second category and her interactive LED coffee table would probably fetch quite a bit on the retail market. You can see a video of the awesome-looking table, below.

It isn’t just the glass, MDF, and pine construction. There’s also a Bluetooth interface to a custom Android application from [Dejan], who collaborated on the project. However, if you aren’t comfortable with the woodworking, [Marija’s] instructions are very detailed with great pictures so this might be a good starter project.

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Smartphone Controlled Periodic Table Of Elements

January 16, 2018 by Tom Nardi 14 Comments

It wouldn’t be much of a stretch to say that here at Hackaday, we’re about as geeky as they come. Having said that, even we were surprised to hear that there are people out there who collect elements. Far be it from us to knock how anyone else wishes to fill their days, but telling somebody at a party that you collect chemical elements is like one step up from saying you’ve got a mold and fungus collection at home. Even then, at least a completed mold and fungus collection won’t be radioactive.

But if you’re going to spend your spare time working on a nerdy and potentially deadly collection, you might as well put it into an appropriate display case. You can’t just leave your Polonium sitting around on the kitchen counter. That’s the idea behind the interactive periodic table built by [Maclsk], and we’ve got to admit, if we get to put it in a case this awesome we might have to start our own collection.

A large portion of this project is building the wooden display case itself as, strangely enough, IKEA doesn’t currently stock a shelving unit that’s in the shape of the periodic table. The individual cells and edge molding are made of pine, the back panel is MDF, and the front of the display is faced off with thin strips of balsa to cover up all the joints. Holes were then drilled into the back of each cell for the LED wiring, and finally the entire frame was painted white.

Each cell contains an WS2812B RGB LED, which at maximum brightness draws 60mA. Given the 90 cells of the display case, [Maclsk] calculated a 5.4A power supply would be needed to keep everything lit up. However, he found a 4A power supply that made his budget happier, which he reasons will be fine as long as he doesn’t try to crank every cell up to maximum at the same time. Control for the display is provided by an Arduino Nano and HC05 Bluetooth module.

The final piece of the project was the Android application that allows the user to control the lighting. But it doesn’t just change colors and brightness, it’s actually a way to visualize information about the elements themselves. The user can do things like highlight certain groups of elements (say, only the radioactive ones), or light up individual cells in order of the year each element was discovered. Some of the information visualizations are demonstrated in the video below, and honestly, we’ve seen museum displays that weren’t this well done.

We last caught up with [Maclsk] when he created a very slick robotic wire cutting machine, which we can only assume was put to work for this particular project. Too bad he didn’t have a robot to handle the nearly 540 soldering joints it took to wire up all these LEDs.

[via /r/DIY]

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